1. Field of the Invention
This invention is concerned with apparatus for stopping movement of an object at a predetermined location.
2. Description of Related Art
Conventional positioning devices of this type are inflicted with a number of problems. The drive motor of the trolley is turned off before the stop position is reached so that the trolley must reach the stop position due to its inertia. However, the suspended loads differ widely. They may reach up to 5 tons. Therefore the positioning device cannot be adjusted optimally. If the adjustment is made so that the trolley with the highest load just about reaches its end position, other trolleys will come to rest before they reach the end position. On the other side, if it is insured that trolleys with a smaller load reach the end position, trolleys with a higher load will suffer severe impact stresses. This will notably lead to impact stresses of the product to be transported, for example an automobile body.
Therefore it is an object of the present invention to provide a positioning device for an electric overhead trolley conveyor whereby the trolleys reach a well-defined precise end position regardless of their mass and without impact stresses and rebound effects.